Chemically, electrolytes are substances that become ions in solution and acquire the capacity to conduct electricity. Among other areas, electrolytes are present in the human body, and the balance of the electrolytes in the human body is essential for normal function of cells and organs. Common electrolytes measured in blood testing include sodium, potassium, chloride, and bicarbonate.
Sodium (Na+) is a major positive ion (cation) in fluid outside of cells. Sodium regulates the total amount of water in the body and the transmission of sodium into and out of individual cells also plays a role in critical body functions. Many processes in the body, especially in the brain, nervous system, and muscles, require electrical signals for communication. The movement of sodium is critical in generation of these electrical signals. Too much (e.g., hypernatremia) or too little (e.g., hyponatremia) sodium therefore can cause cells to malfunction, and extremes in the blood sodium levels (too much or too little) can be fatal. Potassium (K+) is a major positive ion (cation) found inside of cells. The proper level of potassium is essential for normal cell function. Among the many functions of potassium in the body are regulation of the heartbeat and the function of the muscles. A seriously abnormal increase in potassium (e.g., hyperkalemia) or decrease in potassium (e.g., hypokalemia) can profoundly affect the nervous system and increases the chance of irregular heartbeats (arrhythmias), which, when extreme, can be fatal.
Typically, electrolytes are measured by a process known as potentiometry. This method measures the voltage that develops between the inner and outer surfaces of an ion selective electrode. The electrode (membrane) is typically made of a material that is selectively permeable to the ion being measured. This potential is measured by comparing it to the potential of a reference electrode. Since the potential of the reference electrode is held constant, the difference in voltage between the two electrodes is attributed to the concentration of ion in the sample.
However, in certain cases, electrolyte measurement devices do not adequately separate the electrolytes for measurement, and may experience dissociation issues when electrolytes are in water, since water molecules are dipoles and the dipoles orient in an energetically favorable manner to solvate the ions. Accordingly, improvements are needed in electrolyte measurement devices to better measure electrolytes such as potassium, and to expand the applicability of electrolyte measurement to devices such as portable electrolyte measurement devices, hand-held dialysis devices, forced accelerated dialysis and even water filtration.